feat(ui,infra): SvelteKit ui scaffold, Makefile, pre-commit, claude hooks

ui/: SvelteKit 2 + Svelte 5 + Tailwind 4 + shadcn-svelte (luma, lucide)
on bun with ultracite; adapter-static with SPA fallback; theme tokens
taken from msos. Dockerfile gains a bun stage that builds ui/build.
Makefile and pre-commit cover ruff, ty, ultracite and svelte-check;
.claude settings run the matching fixer after edits. docs/PRODUCT.md
captures product truth for the UI work.

.dockerignore

@@ -14,3 +14,10 @@ examples
 **/.ruff_cache
 **/.ty_cache
 README.md
+ui/node_modules
+ui/.svelte-kit
+ui/build
+ui/.vscode
+.claude
+.mcp.json
+Makefile